Field of the Invention
The invention relates to a process for the production of a honeycomb body in which sheet metal layers at least partially having a structure for forming passages through which a fluid can flow are stacked and/or wound. In particular the invention also relates to sheet metal layers with an outer aluminum layer for producing such honeycomb bodies, which are used in particular in exhaust gas systems of motor vehicles.
A honeycomb body of the above-indicated kind is known, for example, from International Publication WO 89/07488, corresponding to U.S. Pat. No. 5,102,743. The honeycomb body serves as a carrier for a catalyst which promotes the conversion of components of an exhaust gas, in particular an exhaust gas from an internal combustion engine, into compounds which are less environmentally polluting. Such honeycomb bodies are exposed to high levels of mechanical and thermal loading. Besides the mechanical and thermal loadings the sheet metal layers are exposed to an atmosphere which promotes corrosion. It is therefore desirable to use sheet metal layers which have a high degree of resistance to corrosion, for producing a honeycomb body.
U.S. Pat. No. 5,366,139 discloses using sheet metal layers which firstly are formed of a layered or laminate material, for producing honeycomb bodies. Such sheet metal layers have at least one layer of chromium-containing steel and at least one substantially aluminum-containing layer. A sheet metal layer of that kind is subjected to a heat treatment, in which the sheet metal layer is substantially homogenized. The expression "homogenization of the sheet metal layer" is used to denote diffusion of the aluminum into the steel so that the result is essentially a single-sheet, sheet metal layer of steel with aluminum.
German Published, Non-Prosecuted Patent Application 29 24 592 discloses various processes for applying brazing material to such sheet metal layers or honeycomb bodies produced therefrom. All such processes require a considerable level of expenditure, resources and additional production steps.